Dry Baked Goods Using Sourdough

I bake a lot and have for years. I have only been experimenting with sourdough for about eight months though and have a question for those who are more experienced.

Except for a chocolate chip cookie recipe posted by PaddyL, any cakes, banana breads, muffins, brownies etc. that I have made using sourdough have come out too dry. This has happened if I follow the recipe exactly and when I have altered it. I do not have this problem with regular quick breads, muffins etc. Only when I use sourdough. The recipes are not all sourdough, they just call for some to be added in addition to everything else. I don't want to add lots of additional fats to everything. Do sourdough enhanced recipes cook faster? That's the only thing that just occurred to me.